pH and concentration

HIGHER GRADE CHEMISTRY CALCULATIONS pH and Concentration pH is related to the concentration of hydrogen ions. e.g [H+(aq)] = 1 x 10-1 mol l -1, pH = 1 [H+(aq)] = 1 x 10-6 mol l -1, pH = 6 Also, in aqueous solution, [H+(aq)] x [OH-(aq)] = 1 x 10-14 mol2 l-2. Worked example 1. What is the concentration of OH-(aq) in a solution with a pH of 5? pH = 5 [H+(aq)] = 1 x 10-5 mol l-1. [H+(aq)] [OH-(aq)] = 1 x 10-14 mol2 l-2. So [OH-(aq)] = mol l-1. = 1 x 10-9 mol l-1. 1 x 10-14 1 x 10-5

Calculations for you to try. 1. What is the pH of 0.01 mol l-1 hydrochloric acid? [H+(aq)] = 1 x 10-2 mol l-1. pH = 2 2. The concentration of [OH-(aq)] is 1 x 10-4 mol l-1. What is the pH of the solution? [OH-(aq)] = 1 x 10-4 mol l-1. H+(aq)] [OH-(aq)] = 1 x 10-14 mol2 l-2. So [H+(aq)] = 1 x 10-10 mol l-1. pH = 10 3. What is the pH of 0.05 mol l-1 sulphuric acid? [H+(aq)] = 2 x 0.05 = 0.1 mol l-1. Formula = (H+)2SO42- [H+(aq)] = 1 x 10-1 mol l-1. Higher Grade Chemistry pH = 1